181

The Tektronix Type 181 is a time mark generator introduced in 1955. There is a benchtop version, the 181, and a rackmount version, the RM181. MOD 110 substitutes a oven-stabilized 1MHZ crystal oscillator, the CO181, thereby achieving 2 parts per million frequency stability in a 24 hour period, the same stability as the 180A.

• Tektronix 181 Manual (PDF)

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  181

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  RM181

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  Block diagram

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  CO181 oven-stabilized oscillator